A ring binder mechanism includes a housing and first and second hinge plates supported by the housing for pivoting movement relative thereto. A first ring member is mounted on the first hinge plate and moveable with the pivoting motion of the first hinge plate relative to a second ring member between a closed position and an opened position. An interlocking formation locks the first ring member and second ring member in the closed position. An actuator is mounted on the housing for movement relative to the housing. The actuator is adapted to pivot the first and second hinge plates and to translate the first hinge plate relative to the second hinge plate in a direction substantially parallel to a longitudinal axis of the housing.